In a bottoming cycle heat recovery apparatus, working fluid exiting the expander is directed to a condenser which removes sufficient heat from the working fluid to return it to liquid state. The heat load of the working fluid entering the condenser can make controlling the temperature of the condenser difficult.
The invention is directed to an apparatus that reduces the heat load on the condenser and is applicable to apparatuses for bottoming cycles such as the Rankine cycle or other thermodynamic cycles.
A bottoming cycle apparatus may include an expansion machine connected in a working fluid circuit to receive working fluid from a waste heat recovery heat exchanger, such as a boiler, vaporizer, or heat exchanger. The working fluid directed to an expansion machine is expanded in the expansion machine to generate usable work or energy. A condenser is connected on the working fluid circuit to receive working fluid from the expander, an accumulator or tank to receive and store condensed working fluid, and a pump connected on the working fluid circuit to receive working fluid exiting the condenser and direct the working fluid under pressure to the boiler. The apparatus according to the invention includes a mixer connected on the working fluid circuit downstream of the expander and upstream of the condenser, the working fluid circuit having a line connected to deliver working fluid to the mixer from downstream of the condenser.
According to the invention, the waste heat recovery apparatus includes a valve on the working fluid circuit downstream of the condenser to control a flow of working fluid to the boiler and the mixer. The valve is preferably located downstream of the pump.
The waste heat recovery apparatus may include a bypass valve disposed on the working fluid circuit between the boiler and the expander and a bypass line connecting the bypass valve and the mixer.
The expander may include a cooling jacket and the apparatus may include a line connected to deliver working fluid to the cooling jacket from downstream of the condenser, the working fluid circuit further including a line connected to deliver working fluid exiting the cooling jacket to the mixer. According to this embodiment, the waste heat recovery apparatus may include a valve disposed on the working fluid circuit downstream of the condenser to control a flow of working fluid to the boiler and the cooling jacket.
According to yet another embodiment, the waste heat recovery apparatus includes a mixer having at least one of a Venturi mixer device, an injector, and an ejector mixer device.